One conventional system used for flood protection utilizes sand bags typically stacked in a trapezoidal dam shape to accommodate greater hydrostatic forces at greater depths of water. When built, the width of the base of the dam is typically much larger than the width at the top. Additionally, the height of such a conventional flood barrier is typically built to be at least 25% to 33% greater than the depth of the flood water.
The U.S. Army Corps of Engineers estimates that a dam or wall of sand bags 4 feet high by 100 feet in length with a trapezoidal shape would require about 7800 sand bags. At a cost of about $0.39 per bag and about $2200 for sand, the total material cost would be about $5242. Additionally, it would take about 180 man hours (just for one person) to fill and stack 7800 sand bags. This cost does not include labor for a second person needed to hold the sand bags open. More sophisticated conventional approaches using sand may be less time and labor intensive, but are typically more expensive and are not readily available.
Even when built, walls of sand bags are prone to leaking because there are gaps between each bag, the bag itself is permeable to water, and tiny gaps between grains of sand provide a pathway for floodwater to penetrate the barrier. Moreover, when sand bags are utilized, the sand bags themselves can be contaminated by flood water and must be disposed of after the flood water subsides. This is also labor intensive and expensive.
Another conventional flood protection system utilizes hydro bags which are impermeable bags filled with water. In operation, the hydro bags are laid out in the desired area to be protected from a flood and then filled with water. However, hydro bags are very expensive, typically costing about $20 for a 4 inch by 6 foot bag, $30 for a 6 inch by 6 foot bag, $85 for a 12 foot by 6 inch bag, and $500 for a 20 inch by 20 foot bag. Additionally, the larger bags, even when empty, are very heavy, cumbersome, and very difficult to place. Thus, the operation could not be performed by elderly or less physically fit persons. Hydro bags also suffer from the problem of having gaps between adjacent bags when stacked.
One conventional apparatus for flood control is disclosed in U.S. Publ. 2007/0243021, incorporated by reference herein. As disclosed therein, vertically placed bladders are disposed around an area to be protected. However, similar as discussed above with relation to the hydro bags, such a system is expensive and is prone to leaking because of the gaps between adjacent bags.